Power and efficiency - Edexcel

1

For which of these could the power be calculated?

2

What are the units for power?

3

Which equation about power is correct?

4

What is the definition of a watt?

5

Which of the following is a definition of power?

6

A hair dryer transforms 10,000 J of energy in 4 s. What is its power?

7

A 60 W lamp is left on for 20 s. How much energy has been transformed?

8

In an electric kettle, what energy is a useful transfer?

9

What is the efficiency percentage of Christmas lights that give out 10 J of light radiation for an electrical transfer of 200 J?

10

What percentage efficiency is an efficiency of 0.25?